An elevator car of an elevator is generally suspended by a wire rope. The wire rope is wound on the driving sheave of a winding machine. The elevator car is lifted and lowered by driving the winding machine and using friction between the rope groove on the sheave surface and the wire rope.
As for a machine room less elevator, the winding machine of which is disposed in the hoistway, the compactness of the winding machine is demanded to reduce the cross sectional area of the hoistway. A means for meeting this demand is to reduce the diameter of the driving sheave. When the diameter of the driving sheave is reduced, it becomes possible to use a low-torque motor in the winding machine to lift and lower the elevator car, enabling the motor to be compact. Accordingly, a highly flexible wire rope that can be easily bent along a driving sheave with a small diameter is demanded.
As a structure that increases the flexibility of a wire rope, a wire rope as disclosed in, for example, Patent Literature 1 is already proposed. That is, the wire rope disclosed in Patent Literature 1 uses fine steel wires, each of which is obtained by wiredrawing an elemental wire of the wire rope to make it fine, the fine steel wire having a breaking force increased to 2600 MPa or more (the breaking force of an elemental wire of a normal A-type elevator wire rope is about 1600 MPa). If a steel wire is made fine, it can be easily bent even when it wound on a driving sheave with a small diameter, so a contact length between the rope groove and the wire rope can be ensured.
However, the steel wire that is made fine in this way is likely to cause a fatigue failure due to fretting wear attributable to the reduction of the cross sectional area of the steel wire. Accordingly, the wire rope disclosed in Patent Literature 1 has a structure in which the circumferences of schenkels formed from fine steel wires and strands are filled with a resin and the entire wire rope is covered with a resin. The resin covering layer has spacer parts that prevent contacts between adjacent schenkels and leaves substantially equal spacings between the schenkels placed along a circumference so that the schenkels are not easily brought into metal contact with one another.